PALMS...
for Texas Landscapes
Robert S. Dewers and Tom L. Keeter
Reprint from the Winter 1972,
TEXAS AGRICULTURAL PROGRESS. Vol. 18, No. 1; pages 20-22. TAP 619 TAP is a quarterly production of the Texas Agricultural Experiment Station and Texas Agricultural Extension Service at Texas A&M University, College Station, Texas.
Click here for a larger map image and the complete article with photos.

PALMS...
for Texas Landscapes
Robert S. Dewers and Tom L. Keeter*

Palms are being used more extensively as ornamental plants over a wider area. These exotic trees and shrubs are adapted to a greater climatic range in Texas than previously considered. Because they provide an interesting, aesthetic environment to the outdoor living of Texans, certain principles in culture and care should be helpful.

Plant When Warm

Plant palms during the growing season when the soil is warm. Palms have a fibrous root system, with each root fiber growing from a root collar When part of the root is severed by moving, it dies back completely. Severed roots must be replaced by new roots if the plant is to survive.

Warm soil temperatures are needed to encourage this new growth or the plant may rot before growth begins. Thus balled palms should be moved in warm weather with several weeks of the growing season remaining before they are subjected to cold soil temperatures. A good rule of thumb is to plant balled palms before September 1 in all but the Lower Rio Grande Valley. If palms must be planted in cold weather, the container-grown plants will be more successful. To prevent shearing of root fibers and to prevent wind-throw, large palms should be braced 1 to 2 years after planting.

Know Cold Temperature Zones

The palm grower should understand the juvenile tenderness to cold temperatures in marginal hardiness zones. Young palms cannot survive as many sub-freezing hours as older palms which have developed protective "wood" around the vascular bundles and the central "shoot." Survival also is probably related to the development of a fibrous root system in relation to freezing soil temperatures. Try to use older palms, preferably those container grown, when subjecting these plants to temperature-limited sites.

Consider Microclimate

The most limiting and extending consideration in palm culture in Texas is the microclimate. Low temperatures may vary several degrees within a few feet. This may result from protection from chilling winds by tree overstory, privacy fences or buildings. It may be caused by radiation from heated homes or other structures. Bodies of water, such as large ponds, lakes or streams, can modify air temperature. Other factors include humidity, wind velocity and presence or absence of direct sunlight the morning after sub-freezing temperatures at the plant-air interface.

The zoned list shows that different species vary in cold tolerance. If the less hardy species are desired, consider the foregoing factors. A more juvenile palm or a more tender species might survive in a mild microclimate, such as near a house on a south exposure. Keeping these influences in mind makes wider selection of palm species possible.

Provide Good Soil

Palms prefer well-drained soil, rich in organic matter and with adequate water and nutrient-holding capacity. Loams and clays with good subsoil drainage are preferred over sands or soils with impervious pans or parent material. In areas of high water tables, the planting grade should be raised. Terraces, berms or raised planters are techniques growers can use to improve subsoil drainage.

On rocky or chalky sites, remove the undesirable topsoil and fill in with loam or silty clay. Well-rotted manure, sludge or composted debris, mixed generously with the backfill, provides productive growing medium.

If added water does not drain downward from the excavated pit within a few hours, a drain tile may be needed.

 

This European fan palm adorns a courtyard at the San Antonio airport.

In the following descriptive list of palm species, the Roman numerals indicate the area in Texas, shown on the hardiness map, where climate is favorable for growing specific species.

With extra protection, such as mulching and wrapping, many species in the list should survive winter temperatures north of the area indicated.

FAN PALMS

Palmate-leafed

Chamaerops humilis —European Fan Palm. A multiple-trunk palm forming a compact crown. Slow grower. Excellent in large planter on patio. I, II

Erythea armata — Blue Hesper Palm. Much overlooked, attractive blue fan palm. Suited to sunny sites and better soils. Its northern hardiness range has not been well-tested. I, II

Livistonia australis — Fountain Palm. Believed hardier and grows taller and faster than L. chinensis. I, II.

Livistonia chinensis — Chinese Fountain Palm. Once believed hardy only in southern Florida, is thriving in San Antonio and Austin. Protect from north wind. Excellent patio pot palm. I, II.

Nannarops ritcheana — Mazari Palm. From arid mountains of Pakistan, bushy habit similar to Saw Palmetto. May prove to be hardiest of palms. I, II, III

Paurotis wrightii — Saw Cabbage Palm. Native to Florida Everglades, this attractive clustered trunk palm survived recent winters in Austin. Thrives in wet soil. I, II

Rhapis excelsa— Lady Palm. Multiple cane-like trunks and slow growth make it an ideal understory or hedge plant in shady protected areas.

Rhapidophyllum hystrix — Needle Palm. Native in Carolinas, low growing habit, prefers semi-shade. I, II, III

Sabal causiarum — Puerto Rico Hat Palm. Attractive large palmetto, thick trunk, long fan-shaped leaves. I, II

Sabal etonia— Scrub Palmetto. A trunk-less palm, native to Florida. Useful as a complementary planting with larger palms. I, II.

Sabal louisiana — Louisiana Palmetto. A slow-growing hardy palm with low trunk and large fronds. I, II, III

Sabal minor —Dwarf Palmetto. Native to Texas. Quite hardy north of Dallas, trunkless, an accessory blue-green palm. I, II, III

Sabal palmetto—Cabbage Palmetto. Taller, faster grower than S. texana, slender trunk. Good landscape specimen. I, II, III

Sabal texana — Texas Palmetto. Native Texas Palm. Has survived severe winters in Dallas-Ft. Worth area. Slow starter, but becomes an attractive tree. I, II, III

Sabal umbraculifera — Hispaniolan Palmetto. Most massive of the palmettos. Thriving in Houston. Heavier trunk than most of this genus. I, II

Trachycarpus fortunei — Windmill Palm. Reputedly the hardiest of palms, has withstood two degrees F. in Dallas. Slower grower, thin hairy fibrous bark cover. Attractive in groups. I, II, III

Washingtonia filifera — California Fan Palm. Thicker trunk, not as tall, but hardier than W. robusta. Specimen planted in 1936 at Fair Park, Dallas, still thriving. Older specimens are surviving in El Paso and Midland. I, II, III

Washingtonia robusta — Mexican Fan Palm. Fast-growing slender trunk, tall, readily available. I, II

 

FEATHER PALMS Pinnate-leafed

Acrocomia total — Gru Gru. Solitary trunk and leaves armed with sharp prickles excludes its use to the hobbyist or botanical garden. I

Arecastrum romanzoffianum (Cocos plumosa) — Queen Palm. A popular palm in warmer areas with graceful arching feathery leaves. Needs some protection from freezing winds. Suffers from manganese deficiency. I

Butia capitata (Cocos australis) — Pindo Palm. Jelly Palm. Slow-growing, arching blue-green fronds, hardy in North 'Central Texas. Several of this genus may prove adaptable to colder areas of the state. Reported thriving in Midland. I, II, III

Jubaea spectabilis—Chilean Honey Palm. Similar in appearance to Canary Island Date Palm, but believed hardier. Growing in Dallas County, but hardiness not yet tested there. I, II

Phoenix canariensis—Canary Island Date Palm. One of the most attractive large ornamental palms. Excellent for parks or roadside planting. I, II

Phoenix dactylifera — Date Palm. Believed hardier than above, but not as attractive. Bluer fronds, thinner trunk,

sprouts from the trunk can be used for propagation. I, II

Phoenix reclinata — Senegal Date Palm. Best known ornamental palm of Africa, it makes an attractive impenetrable screen or hedge. Forms attractive multiple trunks if thinned. Survived 12 degrees at San Antonio Airport. I

Phoenix roebelenii — Pigmy Date Palm. Slow-growing ornamental. Excellent pot plant indoors, but thrives outdoors in shade. I

Phoenix sylvestris — India Date Palm. Shorter leaves and trunk than P. canariensis. Exposes roots at base. Very symmetrical and attractive landscape tree. I, II

 

This attractive scene in a Central Texas home lawn displays Washington, Date, Windmill, Blue Hesper and Fountain palms.

This feather palm is a Pindo Palm, Butia capitata, and has survived near zero degree temperatures in Midland, El Paso and Fort Worth.

Another feather palm, the Canary Island Date Palm, Phoenix canariensis, with its attractive trunk, thrives in Austin's climate

.

This fan palm is the Chinese Fountain Palm, Livistonia chinensis, growing on North St. Mary's Street in San Antonio.

Palm hardiness map of Texas.

Zone I — Average annual minimum temperature (AAMT of 20 to 30 degrees F. or warmer.

Zone II and III — AAMT 10 to 20 degrees.

Zone IV — AAMT 10 degrees or colder. Not recommended for outdoor growing of palms without freeze protection.

 

The map above is the most accurate available, although it would be more useful to palm growers to indicate average daily hours below freezing rather than average minimum temperatures.

 

*Extension horticulturist, Texas Agricultural Extension Service, and city horticulturist, San Antonio.

Scanned by Wilbur Watje in 2006. See: http://www.plantanswers.com/wilbur_que.htm